Powertrain Overspeed Protection via Dynamic Torque Control
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Solution Overview
Problem
Vehicle powertrains can experience uncontrolled speed flares leading to potential damage to engine, torque converter, and transmission components due to overspeed conditions, which existing technologies fail to effectively prevent.
Innovation Solution
A method that monitors transmission input shaft speed and engine speed, determining threshold speeds based on operating conditions to reduce engine torque requests when overspeed is detected, either by a fixed amount or dynamically, to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no overspeed protection control is implemented, then the powertrain can operate without torque restrictions, but overspeed conditions can occur causing damage to engine, torque converter and transmission components
Solution Approach 1:
The control system preemptively reduces engine torque request when approaching threshold speeds during gear shifts, preventing overspeed conditions before they occur. This proactive approach addresses the technical contradiction by preparing protective action in advance rather than reacting after damage occurs.
Solution Approach 2:
The system continuously monitors transmission input shaft speed and engine speed, comparing actual speeds against threshold values, and dynamically adjusts torque requests based on the feedback. This closed-loop control resolves the contradiction by maintaining protection while allowing normal operation within safe parameters.
2Reliability
If engine torque is reduced to prevent overspeed, then component damage is prevented, but powertrain performance and productivity are compromised
Solution Approach 1:
The torque reduction amount is dynamically adjusted based on the degree of speed deviation from thresholds and operating conditions. Rather than applying fixed torque limits, the system modulates torque requests proportionally to the overspeed risk, maintaining maximum performance within safe operating boundaries and resolving the contradiction between protection and performance.
Solution Approach 2:
The control system changes torque request parameters dynamically based on operating conditions (acceleration, deceleration, gear state). By adjusting torque as a variable parameter rather than applying static limits, the system achieves component protection while minimizing impact on overall powertrain productivity and performance.
3Reliability
If threshold speeds are set low to ensure protection, then component safety is improved, but the operating range of the powertrain is restricted
Solution Approach 1:
Threshold speeds are set as preliminary safety boundaries that trigger protective torque reduction before actual overspeed damage can occur. These pre-established thresholds provide adequate safety margins while allowing the powertrain to operate throughout its full designed operating range under normal conditions, resolving the contradiction between safety and adaptability.
Data Source
AI summary
A method of inhibiting an overspeed condition in a vehicle powertrain includes monitoring at least one of an engine speed and a transmission input shaft speed of a torque converter that transfers drive torque between an engine and a transmission and determining an operating condition of the vehicle powertrain. The method further includes determining a first threshold speed based on the operating condition and reducing an engine torque request when the at least one of the engine speed and the transmission input shaft speed exceeds the first threshold speed.